Sub-plenum directional airfoil



FIG. 1 is an isometric front view of the sub-plenum directional airfoil.

FIG. 2 is a bottom plan view thereof;

FIG. 3 is a top view plan view thereof;

FIG. 4 is a front elevation view thereof;

FIG. 5 is a back elevation view thereof;

FIG. 6 is a right side view elevation view thereof; and,

FIG. 7 is a left side elevational view thereof. 

CLAIM The ornamental design for a sub-plenum directional airfoil, as shown, and described. 